Pathophysiology of Reflex Syncope: A Review

Wayne O. Adkisson MD; David G. Benditt MD

Disclosures

J Cardiovasc Electrophysiol. 2017;28(9):1088-1097. 

In This Article

Clinical Management of Reflex Syncope

The focus of this communication has been on the nomenclature and pathophysiology of the reflex syncope syndrome. Clinical guidelines for the management of syncope are available.[2] Updated ACC/AHA/HRS guidelines on the evaluation and management of syncope are in press at this time.[35] Readers are referred to those documents for a comprehensive discussion of the clinical management of reflex syncope. A few key points are noted below.

The cornerstone of management of reflex syncope is patient awareness of, and when possible, avoidance of the triggers for their syncope. Adequate hydration, including increased salt intake (assuming no concern regarding underlying hypertension), is often recommended. Additionally, although most VVS patients are otherwise healthy, the possibility of a contributing disease should always be considered. Elimination of triggers, when possible, is critical.

Thus, patients with cough syncope should be evaluated for why they are coughing. Relief of cough is the primary treatment; smoking and air pollution avoidance is often an important recommendation. When complete relief of coughing cannot be achieved, patients are instructed to lie down, if possible, when having a paroxysm of coughing. This may not always prevent syncope but does help avoid injuries related to syncope.

Other forms of situational syncope are approached in a similar, common sense, fashion. For example, it is important to emphasize the avoidance of excessive alcohol and dehydration in those individuals who have demonstrated susceptibility to micturition syncope. Although not always triggered by straining, regulation of bowel habits is reasonable for the prevention of defecation syncope recurrence. Patients with deglutition syncope should be evaluated for coexisting esophageal pathology.

As noted earlier, there are case reports of permanent pacing being used for many forms of situational syncope. Additionally, pacing does appear to be beneficial in patients with CSS[2] and is generally recommended in this condition since predominance of cardioinhibition seems to be more prevalent in CSS than in other forms of reflex syncope. However, since reflex syncope often has a vasodepressor component that is not reversed by pacing, patients may remain symptomatic although syncope may revert to a less serious problem such as "lightheadedness." In general, the younger the patient, the less evidence there is for pacing therapy for the prevention of any of the reflex faints.

Pacing for VVS remains controversial. Brignole and colleagues[36,37] in the ISSUE-2 and ISSUE-3 trials noted that patients with marked bradycardia, as recorded on an implantable loop recorder (ILR) during spontaneous clinical events, had fewer recurrences with permanent pacing as compared to controls. Further, it appeared that pacing was most effective in those bradycardia cases in which tilt-table testing did not reveal a marked tendency to a vasodepressor physiology. These observations suggested that in highly symptomatic VVS patients with cardioinhibition documented during spontaneous events (usually by an insertable cardiac monitor or ILR) and in the absence of vasodepression susceptibility, as determined by tilt-table testing, who have failed standard therapies, might benefit from pacing. However, the study primarily focused on older patients (i.e., above 40 years of age, and mostly 60+ years of age). Further, prospective testing of this observation is as yet incomplete.

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